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School me about diesels

Eric M.

Eric M.

1/2 ton status
Joined
Dec 10, 2001
Posts
2,142
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Location
Oakland, CA
I've wandered over here from the other forums. I've got 7 GM trucks, 2 wd and 4 wd, all gas. a few I use for work (construction) and the cost of gas is killing me.

I'm considering a few things. Diesel swap, but I'm wondering if the diesels really get better milage or with the cost of diesel where it is, will this really save much? Diesel swap and convert to veggie oil. I've got a client who's linked up with a veggie fuel conversion company here in town that could help out.

Any thoughts on either of these plans?

Also, what is a good choice of diesel engine for an 87 V3500? Is the 6.2 the only factory diesel for the 2nd generation GM trucks? Is it a good one? Are there things I should do to make it better? Other engines I should consider? I don't want to get too carried away ... I know everyone loves the Cummins, but I'm thinking that might be some work!

Thanks,

Eric M.
 
Eric M. said:
I've wandered over here from the other forums. I've got 7 GM trucks, 2 wd and 4 wd, all gas. a few I use for work (construction) and the cost of gas is killing me.

I'm considering a few things. Diesel swap, but I'm wondering if the diesels really get better milage or with the cost of diesel where it is, will this really save much? Diesel swap and convert to veggie oil. I've got a client who's linked up with a veggie fuel conversion company here in town that could help out.

Any thoughts on either of these plans?

Also, what is a good choice of diesel engine for an 87 V3500? Is the 6.2 the only factory diesel for the 2nd generation GM trucks? Is it a good one? Are there things I should do to make it better? Other engines I should consider? I don't want to get too carried away ... I know everyone loves the Cummins, but I'm thinking that might be some work!

Thanks,

Eric M.
Click to expand...

Hey Eric
Welcome to the dark side.
As far as diesl and fuel economy, even with the fuel prices the way they are now, you still benefit a little and you get more pulling power if you are switching from a SBC, if it's a BBC then you will benefit more in fuel economy.
As far as choices there is the 6.2 and there is the newer 6.5 which also came later in Turbo trim for much better power less MPG.
It's pretty straight forward to swap and you can tweak them a little for 0$ to get a little more power.
Veggie use you will get a lot of conflicting opinions but if you want reliability for your company trucks stick with diesel.
If you want to have one in your personnal truck, I would say play with it with the WVO but you will need a lot of prep (filtering, removing moisture,..) and maintenance (changing filters,...) it's still worth it but reliability might be an issue so I would not do it for the company trucks.
I have a bunch of diesels and I will be using WVO in one to see how much trouble it will be.
The 6.2 in stock form in a 2wd truck will get you up to 24MPG but most on average get between 18 and 20MPG, the 4wd tend to get 1-2MPG less.
I was getting 24MPG with my 82 Van with a tired 6.2l
For your trucks you will only need to change the Torque converter and the governor and add a battery unless for some reason you already have 2.
In SF you could probably get away with only one high CCA battery min 1000 CCA.
Everyting else should be the same: Wiring harness, motor mounts, cross members, ...
The radiator can be used from a gas but the diesel preferably uses an oil cooler and has a bigger radiator which will only fit the newer 81-91 core support, so it's good you already did that on all your trucks. :D
The accessories are also interchangable.
Gas tanks need to be flushed and can be used for the diesel.
Any questions just ask, there are plenty of people here that have done it.
 
Thanks Issaam,

I hear you're going to see Robert on Wed. for that 2wd 1 ton suspension stuff. If you still have it, could you send along that wiper electrical clip I need?

By the way, I moved to sunny Oakland. No more S.F. fog (and rust I hope).

Thanks for the info. on diesels, what does WVO stand for? Anyone here do the veggie conversion?

Eric
 
Eric M. said:
Thanks Issaam,

I hear you're going to see Robert on Wed. for that 2wd 1 ton suspension stuff. If you still have it, could you send along that wiper electrical clip I need?

By the way, I moved to sunny Oakland. No more S.F. fog (and rust I hope).

Thanks for the info. on diesels, what does WVO stand for? Anyone here do the veggie conversion?

Eric
Click to expand...

Yeah I was going to ask if you still need it, I have it ready and I will give it to him.
As for WVO it's Wadte Vegetable Oil, meaning used /cooked oil, which makes it more liquid and volatile, burns better than straight vegetable oil and is cheaper since it's free.
It just needs lots of filtering and moisture removal.
 
My '83 half ton averages 17-18 mpg in town, 25+ mpg on the highway. With the dual tanks my real world range is 1000 miles if i'm on the highway all of it.

WVO= waste vegetable oil

I'd stay clear of WVO, especially after seeing the horrifying build-up and engine damage posted up by 4x4byGod on a Jetta that had been running it. It doesn't burn clean. I'd consider running B20 though...which is a blend of regular diesel and 20% Bio-diesel. Around here it's even a few cents cheaper per litre (roughly 10cents/gallon)

Power is comparable to an older stock carb'd 350...

To swap to a diesel isn't that hard really. It is best to have a complete donor truck available though. That gets you all the various little diesel specific things that can otherwise add up.

Maintenance isn't much different, the biggie is you really need to be diligent with the oil changes.

I highly recomend something with overdrive, although in town it doesn't make that much difference. Actual savings are very noticable, in fact I figured my 6.2 swap into my Jimmy paid for itself in under two years. It only took that long because I didn't really drive it that many miles per year. This was also when fuel costs were much lower...

Rene
 
Can you post the link to that damaged Jetta? I am starting to think it might be difficult collecting enough WVO to support a rig that is driven 60+ miles a day. With the problems you're mentioning about WVO and difficulty finding it (I don't have enough free time to hit up every fast food joint in town when I need to gas up), maybe I'd be better off with straight diesel. The swap would be in a 1 ton truck. Not sure if I'd do the 2 wd single rear wheel or the 4x4 dually, but either way, I won't be looking at the same milage you're getting in a 1/2 ton. On the plus side, 50 miles of that daily driving is freeway.

As for overdrive, the 4l80e is the only one I'd consider. I know you guys do a lot of trick work to the 700R, but these are work trucks, I just can't see the 700 standing up to a 1 ton hauling 4k lbs. to a job site. 4L80e are expensive and I'd need the stand alone computer. I have one in my Burb that is slowly rusting into a pile of orange stuff, I'm just not ready to declare it dead and rape it of useful parts.

Any ideas?

Thanks,

Eric M.
 
I'd highly recomend skipping the WVO idea. Use regular diesel with a name brand fuel additive (Stanadyne or Power Service are two that come to mind)

A 6.2 with a TH400 and 4.10's will only get you maybe 15 mpg. Drop down to 3.73's and use an SM 465 4 speed and 16-18 is more likely.

The truck being heavy doesn't really affect fuel mileage so much on a 6.2. It is more important to get it in the right rpm range for highway cruising. The 4L80e would be a good choice, but like it's 3 speed brother the TH400 it's a bit of a power robbing tranny. The ideal rpm range for best fuel economy is 1800 rpm. You'll lose about 1 mpg with every 100 rpm increase of your cruise rpm. My Jimmy used to get 16.5 mpg on the highway. 5" of lift, 39.5" TSL's, 6200 lbs, 6.2 with a SM 465, 4.56's. Cruise rpm was about 2600 rpm.

I just had 3K in the bed of my '83 1/2 ton this weekend...I hardly noticed it and it rode nicer. :D More wouldn't have been a problem, it wasn't on the bumpstops yet. :p:

Rene
 
If you're doing the 2WD truck I'd seriously look at the NV4500. They seem to be reasonably easy to find in the 2WD version (for some reason). A nice brawny manual tranny, but smooth shifting and has a 0.73:1 overdrive.

I swapped one into my 81 Jimmy with 6.2...I wouldn't doubt it'll pull down over 20 mpg on the highway now.

Rene
 
I converted my '79 K10 from a 350 gas motor to a 6.2L (it came with the SM465/NP205 from the factory). With 3/4 ton axles & springs, 4.10 gears, and 285/75R16 load range D M/T tires I was getting 18 mpg highway empty and 15-16 mpg heavily loaded... I drove the wheels off that truck across country several times. The only down side to the 4.10 gears and no OD was a max speed of 65 to be comfortable on the highway but it had better power than the 350 small block and better mileage.

The parts are easy to get, the 6.2's are cheap to buy and they will last longer than a small block given normal maintenence. About the only hitch I ran into on a 73-80 body style was the diesel radiator didn't fit... so I ran a 454 radiator with diesel tanks instead. The 454 fan shroud is a perfect fit on the 6.2L that way as well.
 
Everybody is leaning towards a diesel swap, no WVO. I just don't know if it's worth it for 15 / 16 MPG. For what the swap would cost, I could pick up a 4 cyl. Toyota and Get 30 MPG. If I needed to haul anything large or heavy, could take one of the big trucks.

Gotta think about this a little more ....

Thanks,

Eric M.
 
Eric M. said:
Everybody is leaning towards a diesel swap, no WVO. I just don't know if it's worth it for 15 / 16 MPG. For what the swap would cost, I could pick up a 4 cyl. Toyota and Get 30 MPG. If I needed to haul anything large or heavy, could take one of the big trucks.

Gotta think about this a little more ....

Thanks,

Eric M.
Click to expand...

I would be the first one to try and go with the WVO but I know I can keep up with doing filtering for my purposes, WVO is not clean and you need really good clean fuel so you don't mess up your injectors.
The 6.2 is more fogiving than the newer diesels but if you want the engine to last you still want to be carefull with the use of WVO.
If you think you have the source, and willing to get the quantity for 5-6 trucks prepped, then go for it, like was said, they are cheap and parts are cheap, but down time for you is not cheap so you don't want to break down.
:D
I will be eventually on WVO for all my diesels but i don't have a business running them just personnal, if one goes down, it's no biggie. :rolleyes:
 
the issues with WVO all stem from the fact that its acidic, fresh VO is PH neutral and same with pump diesel (bio manufactured to ATSM standards is as well) the acidic properties are what cause most of the issues.
 
ccatlett1984 said:
the issues with WVO all stem from the fact that its acidic, fresh VO is PH neutral and same with pump diesel (bio manufactured to ATSM standards is as well) the acidic properties are what cause most of the issues.
Click to expand...

That is one aspect I fogot to consider :crazy:
I know I changed my oil religiously at 3 months because it becomes acid and i don't want to eat up my engine from the inside out.
Food for thought.... hmmmm.
 
I would personally go with biodiesel, if you were considering an alternative fuel. It is a more work to setup in the beginning, but in the long run it is easier on the engine if it is made correctly. Also if you get a good system going, it is not too much more difficult than WVO, just do research and do it right the first time. However, if you are crunched for time because you have to work a lot or something, I would ignore alternative fuels because they take more time.
 
mudman83 said:
I would personally go with biodiesel, if you were considering an alternative fuel. It is a more work to setup in the beginning, but in the long run it is easier on the engine if it is made correctly. Also if you get a good system going, it is not too much more difficult than WVO, just do research and do it right the first time. However, if you are crunched for time because you have to work a lot or something, I would ignore alternative fuels because they take more time.
Click to expand...

You mean make my own?
i am already working on that, but I wanted to run the WVO 50% mixed with diesel to save the hastle but if it will kill my engine too soon then i will just make my Bio
 
Look up tossing in a Cummins 4bt and think 30 - 35 MPG:eek1::eek1: Although the power would pretty much kill the purpose of a 3500:D

They did come as an option in Stepsides so adapting to a GM pick-up is fairly easy and readily available cheap.

I did lots of research and came to the conclusion it was certainly doable and a boost of power can be had as well. You'll hear 300hp tossed around but don't expect the engine to last long. I figured 200hp would be a good compromise for power, mileage and durability.

Then I got a 6.5 cheap;)
 
BKinzey said:
Look up tossing in a Cummins 4bt and think 30 - 35 MPG:eek1::eek1: Although the power would pretty much kill the purpose of a 3500:D
Click to expand...

Folks like to throw around big numbers for 4bt mileage, but you aren't going to get 30-35MPG out of it in a K5. From what I have seen they end up getting the same to maybe 2MPG better than the early 6.2's. That is in stock form - bombing one can end up hurting the mileage, but not doing so means you have to live with 120-130HP...
 
why all the talk about 6.2? imo, they arent the best swap (no offence to the guys that already swapped one). go striaght to the 6.5td. i am looking for one right now. im making a road legal pulling truck out of my k5. i was goina build a sbc 400 but a built 6.5 turbo would be so much cooler :D . you get get 300 horse and 500+ tq from a properly built/tuned 6.5. that with 14b rear and 12b front axles, 205 t-case, and good drive shafts behind a sm465= beast. but as far a bang for the buck, i think a stock 6.5 is the way to go. just my 2cents
 
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